The Swedish patent specifications SE 7,307,577-2 and 7,611,511-2 are examples of a practical application of angle gauges which are founded on the technique used in the present invention, namely, the moire effect. In these known devices a moire pattern arises by two gratings being provided on parts which are rotatable relative to one another, whereby a pattern arises which indicates whether the two parts are located at a desired angular position relative to one another or whether they deviate from this angular position. The angle gauges can be provided with a graduated angular scale, by means of which the gauge can be used to obtain a directly readable value, for example, for an object, such as a parabolic antenna, which can be adjusted for different angular positions. The angular position relative to the horizontal plane is arrived at by the one part being made unbalanced so that it continually strives to assume a position which is unchanging relative to the horizontal plane. In these cases it may prove difficult, using the previously known devices, to achieve both a high degree of adjustment accuracy and simplicity of adjustment due to the fact that a high degree of adjustment accuracy is associated with undesirably quick and large motions of the moire pattern for each angular change.
The object of the present invention is to provide a device by means of which a high degree of adjustment accuracy, as well as simplicity of adjustment, can be achieved.